1. Field of the Invention
The present invention is directed to a monitor for an optical signal transmitted between two optical waveguides, and in particular to such a monitor that is readily scaleable to arrays.
2. Description of Related Art
In optical communications systems, tapping off part of the beam to monitor it for a variety of parameters, e.g., wavelength, channel power, system feedback, is often desired. There are various known constructions of optical waveguides, including optical fibers, which include physical alterations, e.g., gratings, notches, in the waveguide structure to tap out a portion of the light traveling therein for a number of applications. Most of these techniques are directed to a non-destructive tapping of the waveguide, since alignment of waveguide end points may be inefficient and difficult to align. However, these solutions involve a relatively high loss of signal, e.g., a few dB, and the actual amount of power being tapped off can be difficult to repeatedly manufacture.
Some solutions do use a direct in-line connection between optical waveguides and tap a portion of the entire beam being transmitted between the waveguides. However, the size and cost of conventional fiber couplers make their use impractical. These solutions also assume that the use of such a system will be at terminal ends of the waveguides and do not disclose use of such a system internal to a continuous waveguide, presumably because the above issues have not been sufficiently addressed.